The invention relates to a method for improving the initial activity of hydrazine with respect to oxygen dissolved in water, with the hydrazine being activated by adding complexes of trivalent cobalt with inorganic ligands as complex constituents. Activated hydrazine is used as an agent to remove oxygen from water, especially from reservoir drinking water and from water used to preserve installations no longer in use, in order to protect containers, pipes, steam boilers, heat exchangers and other installation parts from corrosion.
Various methods have been used to remove oxygen dissolved in water. Hydrazine has been especially preferred which, when adding suitable activators, reacts at low temperatures with oxygen dissolved in water, forming innocuous nitrogen. Cationic and anionic complexes of trivalent cobalt with inorganic ligands as complex constituents are suggested as especially suitable activators (WP C 23 F/224246). Even if these activators are considered favorably, there is still the disadvantage of the concomitantly activated hydrazine not reaching its full reaction velocity with respect to the oxygen dissolved in water, immediately from the start.
It has been suggested to eliminate this deficiency by gassing the activator-rich hydrazine solution with air (WP C 23 F/224247). However, this is disadvantageous in that a separate processing step has to be introduced in order to assure a good initial activity. It is additionally disadvantageous in that the exiting air is burdened with hydrazine vapors when using hydrazine solutions with commercial concentrations, and thus cannot be released into the surrounding air without additional measures.
It is the object of the present invention to improve the initial activity of activated hydrazine with respect to oxygen dissolved in water, in those instances when complexes of trivalent cobalt, with inorganic ligands as complex constituents, are used as activators.
It is thus the object of the invention to develop a suitable activator system, which assures that the hydrazine solution having the aforementioned activators immediately reaches its full reaction velocity with respect to oxygen dissolved in water, eliminating the need for gassing with air.